Sympatric distribution of two species of Alouatta (A. seniculus and A. palliata: Primates) in Chocó, Colombian Amazonas, Peru

Abstract

We studied a zone of sympatry between Alouatta seniculus and Alouatta palliata on the left bank of the Atrato River (Chocó). We located 110 groups of Alouatta, consisting of 81 groups of A. palliata and 29 groups of A. seniculus, recorded between 12 – 300 m a.s.l. Alouatta seniculus was associated principally with arracachal and panganal vegetation of alluvial soils alongside the Atrato River below 50 m altitude, and A. palliata was associated with upland vegetation of gallery forest, primary forest and secondary forest (20-300 m a.s.l.). The average number of animals per group of A. seniculus was 5.59 (range 2-7 individuals) while the average for A. palliata was 6.76 (range 2-18 individuals). No phenotypic evidence of hybridization was detected in contrast to other studies of hybridization of Alouatta. The condition of many of the forests in this study suggests the necessity of a conservation program in order to protect this unique zone of sympatry between the two species.